has my decoder been tampered with?

Discussion in 'DCC & Electronics' started by green_elite_cab, Oct 3, 2006.

  1. green_elite_cab

    green_elite_cab Keep It Moving!

    I have an unknown decoder that came with my SD80MAC locomotive. I got the whole thing for less then the locomotive costs. The hobby shop owner told me it was one of the better DCC decoders that could also operate on DCC ( and this has been a real good hobby shop to me in the past, so i don't see why i shouldn't trust him) In DC, without the decoder, it runs fine. However, in DCC, there are several problems.

    the first thing i noticed was that the lights would turn on and off whenevery i adjusted the speed. I wasn't sure why it was doing that. i kept running it though, because it seemed to be working motor wise. I hit the speed step button to got to 128, and the locomotive wouldn't start. I hit the speed step button again and set it to 14 speed steps, in which it ran fine, and the lights worked, but now makes a loud buzzing noise, and stop and stutters at low speeds.

    At this point i figured that this decoder might have been a lower end decoder, but i popped open the shell to get a look at it. It appears to be missing a wire, and the decder end looks tampered with. there is hard, crumbly stuff coating the ends of the wires.the orange, grey, and black wires are bunched together by that stuff as well as the red and blue wires. the white and yellow wires seem untouched, but they go deeper into the shrink wrapping. the blue wire appeared to have just detached from the 8 pin plug now, but it may have been loose earlier. additionally, the terminal on the plug between the white and red wires was empty, and i figure an imporant wire probably goes there.

    is this just a crappy decoder, or is something wrong with it?

  2. green_elite_cab

    green_elite_cab Keep It Moving!

    Apperently kato has a problem with first production SD80s, but i'm not sure mine is one of them.

    the decoder has black shrink wrap that only says made in china on it.
  3. Thoroughbreed

    Thoroughbreed Member

    This is what ur pin should look like on the 8 pin plug, if the blue is disconnected, it goes right next to the red. the blue will cause lights no to function, and if loose will prob short decoder out. Can try to put back together and check function then.

    Attached Files:

  4. Thoroughbreed

    Thoroughbreed Member

  5. green_elite_cab

    green_elite_cab Keep It Moving!

    Well, in the time that i posted that and went down stairs to repair the blue wire, the black and gray wires disconnected. I resoldered them all back together carefully.

    i'm starting to think this is a MRC decoder, because it looks like one of theirs from their site.

    however, all of their decoders are set up to be able to run on more than one speed step.

    my loksound manual ( i know its a different decoder but i think that applies) says that if something is incorrectly plugged in, it could cause the symptoms i'm expieriencing, such as the weird thing with the lights and speed steps.
  6. MasonJar

    MasonJar It's not rocket surgery

    If you have the decoder reassembled to what you think is original condition, can you reset it to factory specs? How you do that may depend on your DCC system and what the decoder actually is. But that may solve some of the erractic problems by removing whatever programming the previous owner did.

  7. green_elite_cab

    green_elite_cab Keep It Moving!

    yeah i'm definitely going to try that right now. the only problem is im not sure how to reset it without knowing who's decoder it is, unless the reset CV is the same for all.
  8. green_elite_cab

    green_elite_cab Keep It Moving!

    i set CV 125 to 1 and it did nothing to improove the decoder.
  9. green_elite_cab

    green_elite_cab Keep It Moving!

    yeah, I suppose this decoder is damaged goods, it only runs on 14 speed steps.
  10. Jim Krause

    Jim Krause Active Member

    Does that crumbly stuff that you were talking about earlier smell like burned insulation?
  11. MasonJar

    MasonJar It's not rocket surgery

    What are the spec's for the decoder you think it is? ie. is it limited to 14 steps, etc?

    Jim has an interesting point too - does the residue look or smell funny? Could it have been the original shrink wrap or maybe double sided foam tape (sometimes used to mount decoders with wire harnesses)?

  12. green_elite_cab

    green_elite_cab Keep It Moving!

    i noticed no smell.
  13. green_elite_cab

    green_elite_cab Keep It Moving!

    yeah, it kinda looks like a light yellow/amber color, but i noticed no smell, although some of it was brittle. it looks to me liek the shrink warp was attached the way it is now, but i wouldn't be surprised, considering how many wires i needed to solder back onto the 8 pin plug (i soldered them right) if someone tried to solder wires back onto the decoder.

    I have no clue what kind it is.

    i was reading in my MRC prodigy express manual that you can program CV29 to be 14 speed steps only, but i attempted to reset the locomotive with CV125 and nothing changed. could there be a programming problem?

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